Patients with malignant lymphomas which are apparently clinically localized (stage I or stage II) undergo staging laparotomy to detect occult foci of intra-abdominal tumor. Patients with negative laparotomy findings (pathological stage I or II) are then randomized to receive either a) radiation therapy alone or b) radiation therapy followed by 6 courses of combination therapy utilizing cytoxan, vincristine and prednisone. Patients who are found to have at least stage III disease are treated with combination chemotherapy under a different protocol. Several patients with apparently localized supradiaphragmatic malignant lymphoma have been found at laparotomy to have occult disease below the diaphragm which would not have been properly treated had local therapy been given on the basis of clinically apparent disease only. Eight patients whose staging laparotomies were entirely negative were randomized as described above. Relapses have been seen in both study groups. Too few patients have been accrued at this time to determine the value of adjuvant chemotherapy in this regimen.